立方晶系Ca_2Si声子色散和热力学性质的第一性原理计算（英文）  

First-principle Calculation on Phonon Dispersion and Thermodynamic Property of Cubic Ca_2Si

作　　者：岑伟富 杨吟野[2,3] 

机构地区：[1]贵州民族大学大学生创新创业指导中心,贵阳550025 [2]贵州民族大学,贵州省教育厅光电信息处理与分析特色重点实验室,贵阳550025 [3]贵州民族大学材料科学与工程学院,贵阳550025

出　　处：《人工晶体学报》2017年第11期2260-2265,共6页Journal of Synthetic Crystals

基　　金：Natural Science Foundation of Guizhou Province Education Department([2015]428);The Science and Technology Foundation of Guizhou Province(LH[2015]7218,LH[2016]7077);The Youth Science and Technology Talents Growth Fund Program of Guizhou province Education Department(KY[2016]166);Innovation Group Major Program of Guizhou Province(KY[2016]029)

摘　　要：采用模守恒贋势和超软贋势两种方法分别计算立方晶系Ca_2Si的声子色散关系、声子态密度和热力学特性。运用线性响应方法和有限位移方法确定立方晶系Ca_2Si的声子色散关系和声子态密度,得到立方晶系Ca_2Si的声子振动模式是各向异性,且立方晶系的Ca_2Si是不稳定结构。在声子色散关系确定的基础上分别计算定容热容、焓、熵和自由能随温度的变化关系,得到Cv-T曲线在低温条件下符合德拜第三定律;当T=1000K时,立方晶系Ca_2Si的热熔Cv=21 J·mol^(-1)·K(-1);在高温条件下,随着温度的增加Cv→3R。通过分析声子色散、振动关系和热力学特性得到立方晶系Ca_2Si的振动系统由声子和电子组成。Phonon dispersions, density of phonon states and thermodynamic property of cubic Ca2Si have been calculated by the Norm-Conserving method and Ultra Soft Pseudo-Potential method, respectively. The phonon dispersion and density phonon states of cubic Ca2Si have been confirmed by linear response method and finite displacement method. The result of phonon dispersion and density phonon states show that cubic phase was an unstable structure and the phonon vibration was anisotropic. The heat capacity, enthalpy, entropy and free energy were changed with temperature changing, and the Cv-T curve conformed to the Debye third power law in the low temperature condition. The heat capacity Cv = 21 J · mol -1 ·K_1 at 1000 K, in the high temperature condition the CF-〉-3R with the temperature increasing. The results of the study on the dispersion of phonon, phonon density and thermodynamic property were obtained that the oscillatory systems were formed with phonon and electron.

关 键 词：Ca2Si 声子色散 热力学性质 第一性原理 

分 类 号：O472[理学—半导体物理]